Biliary atresia is characterized by what primary change?

• A. Atrophy of the bile ducts causing obstruction of bile flow
• B. Overproduction of bile acids
• C. Hypersecretion of pancreatic enzymes
• D. Intestinal bile reflux

Answer: (A)

The primary change in biliary atresia is obstruction of bile flow due to congenital obliteration of the extrahepatic bile ducts. Because the ducts are blocked, bile cannot reach the intestines, causing cholestasis and conjugated hyperbilirubinemia. The bile ducts themselves become fibrotic and eventually obliterated, rather than simply increasing production or secretion of bile. Clinically this presents in newborns with persistent jaundice, pale stools, dark urine, and liver enlargement, and without treatment can progress to cirrhosis. The other options describe processes that are not the fundamental defect in biliary atresia.